It is generally known to prepare polysiloxanes by the aqueous hydrolysis of halosilanes, commonly using acid catalysis. Further, in alternative methods, it is known to prepare polysiloxanes by non-aqueous reactions, for example by reacting chlorosilanes with alcohols. In yet another example of the preparation of polysiloxanes, there is shown in U.S. Pat. No. 4,578,494, issued Mar. 25, 1986 to Marko, et al., that certain metal oxides can be used in conjunction with sulfolanes to "hydrolyze" chlorosilanes to polysiloxanes without the use of water. This patent discloses an extensive review of the literature regarding the use of such metal oxides for that purpose, but does not deal with the metal oxide of the instant invention.
In a most recent article, "Selenium Dioxide Catalyzed Conversion of Alcohols to Alkyl Chlorides by Chlorotrimethylsilane", J. Org. Chem. 1988, 53, 3634-3637, Lee, J. G. and Kang, K. K., describe the use of selenium dioxide as an aid in the preparation of alkyl chlorides using alcohols and certain chlorosilanes. In this article, at page 3636, the authors describe the reaction as being one in which the selenium dioxide is converted in situ to selenium oxychloride which they describe as a mild chlorinating agent for alcohols, the advantage being that selenium dioxide cannot escape out of the reaction mixture. The reaction is described thus: ##STR1## wherein there is was also shown at page 3635 the reaction forming the intermediate selenium oxychloride, viz. ##STR2## it being noted that hexamethyldisiloxane is formed in the reaction. The use of trimethylchlorosilane and the formation of the hexamethyldisiloxane would be entirely expected from researchers seeking alkyl halides, since the alkyl halides have boiling points far greater than that of hexamethyldisiloxane and the separation of the alkyl halides is enhanced thereby. Thus, chlorotrimethylsilane was virtually the only chlorosilane used by the authors in order to obtain a siloxane. However, the authors pointed out, at page 3636, column 2, that the reactions they were dealing with did produce oligomers and polymers of dimethylsiloxane as byproducts from the reaction of dimethyldichlorosilane, and they also reacted trichloromethylsilane with the alcohols, without identifying the resulting products, the authors only noting that the " . . . catalyzed chlorination of alcohols by trichloromethylsilane gave a lower yield of alkyl halides. The reason is not clear yet, but there seems to be a competing reaction of the more reactive trichloromethylsilane with alcohols to produce alkoxysilanes." Thus, the authors of this article recognized that they obtained the products that are obtained when siloxanes are not formed such as alkoxychlorosilanes and fully alkoxylated materials but were not aware of the formation of identifiable materials.
They failed to recognize the value of the use of similar reactions to produce commercially viable disiloxanes and cyclic siloxanes, especially those having phenyl, higher alkyl, and certain reactive organic substituents.
The inventors herein, seeking a catalyst that is neither acid or base, so that the siloxanes can be formed without destroying the substituent groups on the siloxanes in the method, have discovered that disiloxanes and cyclic siloxanes having phenyl groups, higher alkyl groups, and certain reactive organic groups can be prepared by the use of selenium dioxide as the catalyst.